Elad Alon | f88aa97 | 2019-04-04 09:43:54 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2019 The WebRTC project authors. All Rights Reserved. |
| 3 | * |
| 4 | * Use of this source code is governed by a BSD-style license |
| 5 | * that can be found in the LICENSE file in the root of the source |
| 6 | * tree. An additional intellectual property rights grant can be found |
| 7 | * in the file PATENTS. All contributing project authors may |
| 8 | * be found in the AUTHORS file in the root of the source tree. |
| 9 | */ |
| 10 | |
| 11 | #ifndef MODULES_RTP_RTCP_SOURCE_RTP_SEQUENCE_NUMBER_MAP_H_ |
| 12 | #define MODULES_RTP_RTCP_SOURCE_RTP_SEQUENCE_NUMBER_MAP_H_ |
| 13 | |
| 14 | #include <cstddef> |
| 15 | #include <cstdint> |
Elad Alon | f88aa97 | 2019-04-04 09:43:54 | [diff] [blame] | 16 | #include <deque> |
| 17 | |
| 18 | #include "absl/types/optional.h" |
| 19 | |
| 20 | namespace webrtc { |
| 21 | |
| 22 | // Records the association of RTP sequence numbers to timestamps and to whether |
| 23 | // the packet was first and/or last in the frame. |
| 24 | // |
Artem Titov | 913cfa7 | 2021-07-28 21:57:33 | [diff] [blame] | 25 | // 1. Limits number of entries. Whenever `max_entries` is about to be exceeded, |
Elad Alon | f88aa97 | 2019-04-04 09:43:54 | [diff] [blame] | 26 | // the size is reduced by approximately 25%. |
| 27 | // 2. RTP sequence numbers wrap around relatively infrequently. |
| 28 | // This class therefore only remembers at most the last 2^15 RTP packets, |
| 29 | // so that the newest packet's sequence number is still AheadOf the oldest |
| 30 | // packet's sequence number. |
| 31 | // 3. Media frames are sometimes split into several RTP packets. |
| 32 | // In such a case, Insert() is expected to be called once for each packet. |
| 33 | // The timestamp is not expected to change between those calls. |
| 34 | class RtpSequenceNumberMap final { |
| 35 | public: |
| 36 | struct Info final { |
| 37 | Info(uint32_t timestamp, bool is_first, bool is_last) |
| 38 | : timestamp(timestamp), is_first(is_first), is_last(is_last) {} |
| 39 | |
| 40 | friend bool operator==(const Info& lhs, const Info& rhs) { |
| 41 | return lhs.timestamp == rhs.timestamp && lhs.is_first == rhs.is_first && |
| 42 | lhs.is_last == rhs.is_last; |
| 43 | } |
| 44 | |
| 45 | uint32_t timestamp; |
| 46 | bool is_first; |
| 47 | bool is_last; |
| 48 | }; |
| 49 | |
| 50 | explicit RtpSequenceNumberMap(size_t max_entries); |
| 51 | RtpSequenceNumberMap(const RtpSequenceNumberMap& other) = delete; |
| 52 | RtpSequenceNumberMap& operator=(const RtpSequenceNumberMap& other) = delete; |
| 53 | ~RtpSequenceNumberMap(); |
| 54 | |
Elad Alon | 28d13cb | 2019-04-06 19:09:30 | [diff] [blame] | 55 | void InsertPacket(uint16_t sequence_number, Info info); |
| 56 | void InsertFrame(uint16_t first_sequence_number, |
| 57 | size_t packet_count, |
| 58 | uint32_t timestamp); |
Elad Alon | f88aa97 | 2019-04-04 09:43:54 | [diff] [blame] | 59 | |
| 60 | absl::optional<Info> Get(uint16_t sequence_number) const; |
| 61 | |
| 62 | size_t AssociationCountForTesting() const; |
| 63 | |
| 64 | private: |
| 65 | struct Association { |
| 66 | explicit Association(uint16_t sequence_number) |
| 67 | : Association(sequence_number, Info(0, false, false)) {} |
| 68 | |
| 69 | Association(uint16_t sequence_number, Info info) |
| 70 | : sequence_number(sequence_number), info(info) {} |
| 71 | |
| 72 | uint16_t sequence_number; |
| 73 | Info info; |
| 74 | }; |
| 75 | |
| 76 | const size_t max_entries_; |
| 77 | |
| 78 | // The non-transitivity of AheadOf() would be problematic with a map, |
| 79 | // so we use a deque instead. |
| 80 | std::deque<Association> associations_; |
| 81 | }; |
| 82 | |
| 83 | } // namespace webrtc |
| 84 | |
| 85 | #endif // MODULES_RTP_RTCP_SOURCE_RTP_SEQUENCE_NUMBER_MAP_H_ |